Audiologists generally utilize the application of a molding composition used to make impressions of ear canals which are sent to laboratories for the purpose of duplicating and creating an ear plug. These ear plugs are made from various materials which are then hollowed out and sealed to prevent water intrusion. This practice is very common but delays exist between when the patient receives the plug and when the impression is taken. Usually requiring a week or more for the patient to return to be fitted with the final ear plug.
Some molding material is used which is molded in the office and is considered the final ear plug. These plugs do not float, are heavy and sink when put in water. Should they be dropped or come loose from the ear in water, such as a pool or the beach, they sink which makes them difficult to find and easy to lose.
Generally, silicone impression material is used for this application as it is considered non-toxic and gives very good reproduction of the impression.
As a binder in these compositions silicone reactive fluid is employed which is mixed with various fillers such as calcium carbonates, silica, and clays to create a putty-like composition which is syringed or hand packed into the ear canal. This material cures in a short amount of time and is removed and sealed with a glaze. The final product varies in hardness, has a specific gravity greater than one and sinks when immersed in water.
In U.S. Pat. No. 4,849,456 to Champion, a casting composition for marble products is disclosed for shaped bathroom products which contains ceramic spheres and plastic spheres. The compound includes an average diameter of plastic spheres significantly less than the diameter of ceramic spheres. The hollow spheres are said to produce a lighter weight composition and the plastic spheres are present in the composition to cushion the ceramic spheres during handling, mixing, and casting of the filler composition. The plastic spheres having a diameter of 3 to 5 microns and the ceramic spheres having a diameter of 10 to 300 microns.
In U.S. Pat. No. 4,528,303 to Segaud et al, a polymer/filler molding composition consisting of a polymeric matrix, an inorganic reinforcing filler and a coupling agent consisting of enstatite and silica prepared by the calcination of a precursor clay. The compositions may contain calcium carbonates, titanium dioxide, silica, aluminosilicate, talc, wollastonite, and calcium sulfate as reinforcing fillers. The said elastomeric silicone compositions are intended to be made from products obtained by crosslinking, under the action of heat.
Although various types of fillers are disclosed for inclusion in base compositions for molding, the final compositions are typically of substantial weight and do not achieve optimum application characteristics, particularly where hand mix and syringing are required. Consequently, the search continues for ear molding compositions which include fillers which reduce weight and may be floatable in water.